Field of the Invention
The present invention relates to a Physical Downlink Control Channel (PDCCH) detection method and device in wireless communication.
Description of the Prior Art
The Long Term Evolution (LTE) project is the largest new technology research and development project started by the 3rd Generation Partnership Project (3GPP) in recent years, and the technology with Orthogonal Frequency Division Multiplexing/Frequency Division Multiple Access (OFDM/FDMA) being the core is regarded as a “4G” technology. LTE will become the most common wide area broadband mobile communication system globally in the future, and all 2G/3G/3.5G technologies will be integrated and collectively evolve to an LTE/LTE-Advanced (LTE/LTE-A) stage.
In order to support Multimedia Broadcast Multicast Service (MBMS), the LTE/LTE-A introduces a Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) subframe. In an MBSFN subframe, the first one or two symbols are used for transmitting a PDCCH, and the other symbols are used for bearing a Physical Multicast Channel (PMCH) to transmit MBMS information. Definitely, the MBSFN subframe may be an idle subframe, and does not bear a PMCH.
On the other hand, as the smart phone market grows rapidly, a mobile communication network is required to bear a huge capacity pressure to support more and more User Equipments (UEs). Therefore, how to increase a capacity of each cell becomes an issue in the 3GPP. One method to solve the problem is to increase a capacity of the PDCCH, that is, to expand the existing common PDCCH to obtain an Enhanced-PDCCH (E-PDCCH). FIG. 1 is an exemplary view of an E-PDCCH containing non-MBSFN subframe expanded in a time domain and in a frequency domain, wherein the horizontal direction represents the time domain, and the vertical direction represents the frequency domain. For simplicity and convenience, FIG. 1 does not show other possibly contained signals or signaling, such as a reference signal, a Physical HARQ Indicator Channel (PHICH), and a Physical Control Format Indicator Channel (PCFICH). According to FIG. 1, in the time domain, the first three symbols of each subframe are used for a common PDCCH (the drawing only shows a scenario where the first 3 symbols are all used for the common PDCCH), and the remaining symbols of the subframe are used for transmitting a Physical Downlink Shared Channel (PDSCH). If an E-PDCCH is required to be transmitted, a part of the PDSCH is used for transmitting the E-PDCCH.
However, how to schedule an E-PDCCH in an MBSFN subframe is still an unsolved difficult problem. The reason is that a non-idle MBSFN subframe (that is, having a PMCH) does not have a capacity to bear the E-PDCCH. If it is simply required that a UE configured to perform scheduling through the E-PDCCH always detects the E-PDCCH in each MBSFN subframe and ignores whether the MBSFN subframe can carry the E-PDCCH, once a certain subframe is required to transmit the PMCH, the UE cannot receive an uplink (UL) grant required by the UE, and cannot send uplink data through a subsequent subframe. Further, if most MBSFN subframes are non-idle, detection of the E-PDCCH in each MBSFN subframe inevitably wastes the power of the UE.